Fix type for register(kwargs) (#788)

gymnasium/envs/registration.py

@@ -567,7 +567,7 @@ def register(
     disable_env_checker: bool = False,
     additional_wrappers: tuple[WrapperSpec, ...] = (),
     vector_entry_point: VectorEnvCreator | str | None = None,
-    **kwargs: Any,
+    kwargs: dict | None = None,
 ):
     """Registers an environment in gymnasium with an ``id`` to use with :meth:`gymnasium.make` with the ``entry_point`` being a string or callable for creating the environment.
 
@@ -587,7 +587,7 @@ def register(
         disable_env_checker: If to disable the :class:`gymnasium.wrappers.PassiveEnvChecker` to the environment.
         additional_wrappers: Additional wrappers to apply the environment.
         vector_entry_point: The entry point for creating the vector environment
-        **kwargs: arbitrary keyword arguments which are passed to the environment constructor on initialisation.
+        kwargs: arbitrary keyword arguments which are passed to the environment constructor on initialisation.
 
     Changelogs:
         v1.0.0 - `autoreset` and `apply_api_compatibility` parameter was removed
@@ -598,6 +598,8 @@ def register(
     global registry, current_namespace
     ns, name, version = parse_env_id(id)
 
+    if kwargs is None:
+        kwargs = dict()
     if current_namespace is not None:
         if (
             kwargs.get("namespace") is not None
@@ -621,7 +623,7 @@ def register(
         max_episode_steps=max_episode_steps,
         order_enforce=order_enforce,
         disable_env_checker=disable_env_checker,
-        **kwargs,
+        kwargs=kwargs,
         additional_wrappers=additional_wrappers,
         vector_entry_point=vector_entry_point,
     )